JP2005077740A - Hologram recording material, hologram recording medium, and method for manufacturing hologram recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram recording material containing a metal oxide and having high diffraction efficiency, a hologram recording medium, and a method for manufacturing the hologram recording material. <P>SOLUTION: The hologram recording material contains metal oxide particles, a polymerizable monomer, and a photoinitiator which initiates the polymerization of this monomer upon photoirradiation. The metal oxide particles are surface-treated with a surface treating agent in which a hydrophobic group and a functional group which can combine with a hydroxyl group on the surfaces of the metal oxide particles by dehydration condensation are combined to a metal atom selected from the group consisting of titanium, aluminum, zirconium, and chromium. Another hologram recording material related to this invention contains metal oxide particles, a polymerizable monomer, and a photoinitiator which initiates the polymerization of this monomer upon photoirradiation, wherein the metal oxide is surface-modified with a group comprising a metal atom and a hydrophobic group combining to this metal atom, wherein the metal atom is selected from the group consisting of titanium, aluminum, zirconium, and chromium. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hologram recording material, a hologram recording medium, and a method for producing a hologram recording material.

Conventionally, there is known a hologram recording material including a resin, a polymerizable monomer, and a photopolymerization initiator that polymerizes the monomer when irradiated with light (see, for example, Patent Document 1).
JP 2000-47552 A

  In recent years, development of a hologram recording material with higher diffraction efficiency has been demanded. Then, the inventors of the present invention are for holograms in which a polymerizable monomer, a metal oxide fine particle that is an inorganic compound different from this monomer, and a photopolymerization initiator that polymerizes the monomer when irradiated with light are mixed. Recording materials were examined.

  However, the hologram recording material containing such a metal oxide has a problem that the diffraction efficiency is not sufficient.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a hologram recording material, a hologram recording medium, and a method for producing a hologram recording material that contain a metal oxide and have high diffraction efficiency.

  The hologram recording material according to the present invention includes metal oxide particles, a polymerizable monomer, and a photopolymerization initiator that starts polymerization of the monomer when irradiated with light, and the metal oxide particles include: The metal atom is surface-treated with a surface treatment agent in which a hydrophobic group and a functional group capable of dehydration condensation with a hydroxyl group on the surface of the metal oxide particle are bonded. The metal atom is selected from the group consisting of titanium, aluminum, zirconium, and chromium. Has been.

Further, the hologram recording material according to another aspect of the present invention includes metal oxide particles, a polymerizable monomer, and a photopolymerization initiator that starts polymerization of the monomer when irradiated with light. -M-R ¹ _n group (where M is any element selected from the group consisting of titanium, aluminum, zirconium, and chromium, R ¹ is a hydrophobic group, and n is a natural number) on the surface of the product particle Are combined.

  The hologram recording medium according to the present invention includes a base material and a recording layer formed on the base material, and the recording layer is irradiated with light from metal oxide particles, a polymerizable monomer, and light. And a photopolymerization initiator for initiating polymerization of the monomer, wherein the metal oxide particles have a metal atom and a hydrophobic group and a functional group capable of dehydration condensation with a hydroxyl group on the surface of the metal oxide particle. The metal atom is selected from the group consisting of titanium, aluminum, zirconium, and chromium.

A hologram recording medium according to another aspect of the present invention includes a base material and a recording layer formed on the base material, and the recording layer is irradiated with metal oxide particles, a polymerizable monomer, and light. And a photopolymerization initiator for initiating polymerization of the monomer, and -M-R ¹ _n group (where M is titanium, aluminum, zirconium, or chromium) on the surface of the metal oxide particles. Any element selected from the group, R ¹ is a hydrophobic group, and n is a natural number) is bonded.

  Further, a recorded hologram recording medium according to the present invention comprises a base material and a recording layer formed on the base material and recorded with interference fringes, the recording layer comprising metal oxide particles and photopolymerization. The metal oxide particles are surface-treated with a surface treatment agent in which a hydrophobic group and a functional group capable of dehydration condensation with a hydroxyl group on the surface of the metal oxide particle are bonded to a metal atom. The metal atom is selected from the group consisting of titanium, aluminum, zirconium, and chromium.

A recorded recording medium according to another aspect of the present invention includes a base material and a recording layer formed on the base material and recorded with interference fringes. The recording layer includes metal oxide particles, light A polymer formed by polymerization, and the surface of the metal oxide particles has a -M-R ¹ _n group (where M is any one selected from the group consisting of titanium, aluminum, zirconium, and chromium). Element, R ¹ is a hydrophobic group, and n is a natural number).

  Furthermore, in the method for producing a hologram recording material according to the present invention, the metal oxide particles are divided into metal atoms selected from the group consisting of titanium, aluminum, zirconium, and chromium, with hydrophobic groups and hydroxyl groups on the surface of the metal oxide particles. A surface treatment with a surface treatment agent bonded with a functional group capable of dehydration condensation, a surface-treated metal oxide particle, a polymerizable monomer, and a photopolymerization initiator that polymerizes the monomer when irradiated with light; Mixing.

  According to these, a hologram recording material having high diffraction efficiency can be obtained. Compared to hologram recording materials that use metal oxide particles that are surface-modified with a surface treatment agent in which a hydrophobic group and a hydroxyl group on the surface of the metal oxide particle and a functional group capable of dehydration condensation are bonded to silicon atoms. Efficiency is high enough.

  Thereby, a hologram recording material, a hologram recording medium, and a method for producing a hologram recording material having sufficiently high diffraction efficiency are provided, and high-density recording can be realized.

  First, the hologram recording material and the hologram recording medium according to the present embodiment will be described.

  As shown in FIG. 1, a hologram recording medium 1 according to this embodiment includes a plate-like base material 20, a hologram recording material 30 as a recording layer formed on the base material 20, and a hologram recording. A protective transparent plate 40 formed on the material 30 is provided. Here, the material of the base material 20 and the protective transparent plate 40 is not particularly limited, and examples thereof include glass, PET, PP, PE, and an acrylic resin.

  The hologram recording material 30 according to this embodiment includes metal oxide fine particles, a polymerizable monomer, and a photopolymerization initiator that polymerizes the monomer when irradiated with light having a predetermined intensity. Yes. Monomers and metal oxide particles are dispersed with each other.

  The polymerizable monomer is not particularly limited, and examples thereof include a fluorine-containing monomer, an acrylic monomer, an epoxy monomer, and polysilsesquioxane. In particular, a so-called photopolymerizable monomer that can be easily initiated by a photopolymerization initiator is preferred.

  Examples of the monomer containing fluorine include vinyl fluoride, vinylidene fluoride, ethylene trifluoride, tetrafluoroethylene, and perfluorobutenyl vinyl ether. Moreover, as a monomer containing fluorine, a mixture of two or more monomers including one or more fluororesin monomers may be used. Specifically, tetrafluoroethylene / hexafluoropropylene, ethylene / tetrafluoroethylene , Ethylene / trichloroethylene copolymer, tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride, tetrafluoroethylene / perfluoroalkyl ether, fluoroethylene / vinyl ether, tetrafluoroethylene / hexafluoropropylene / perfluoro Combinations such as alkyl vinyl ethers may be mentioned. Two or more of these can be used in combination.

  Acrylic monomers include acrylic acid and acrylic acid esters (eg, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, p-chlorophenyl acrylate, 2-phenylethyl acrylate, 2-phenoxyethyl acrylate, trimethylolpropane triacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, benzyl acrylate, 2- (1-naphthyloxy acrylate) ) Ethyl, 2,2-di (p-hydroxyphenyl) propane diacrylate, ethoxylated bisphenol A diacrylate, di (3-acryloxy-2-hydroxypropyl) ether of bisphenol A, Sphenol A-diacrylate, etc.), methacrylic acid and methacrylic acid esters (for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, methacrylic acid) P-chlorophenyl acid, 2-phenylethyl methacrylate, 2-phenoxyethyl methacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate, 2,2-di (p -Hydroxyphenyl) propane dimethacrylate, polyoxyethyl-2,2-di (p-hydroxyphenyl) propane dimethacrylate, bisphenol A di (2-methacryloxyethyl) Di (2-methacryloxyethyl) ether of tetrachloro-bisphenol A, di (3-methacryloxy-2-hydroxypropyl) ether of tetrabromo-bisphenol A, di (2-methacryloxyethyl) ether of tetrabromo-bisphenol A And di (3-methacryloxy-2-hydroxypropyl) ether of diphenolic acid, 1,4-benzenediol dimethacrylate, and the like. These can be used in combination of two or more.

  Epoxy monomers include diglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, 1,4-bis (2,3-epoxypropoxyperfluoroisopropyl) cyclohexane, sorbitol polyglycidyl ether, trimethylolpropane polyglycidyl ether, 1, 6-hexanediol diglycidyl ether, resorcin diglycidyl ether, polyethylene glycol diglycidyl ether, phenyl glycidyl ether, p-tertiarybutylphenyl glycidyl ether, adipic acid diglycidyl ester, orthophthalic acid diglycidyl ester, dibromophenyl glycidyl ether, dibromo Neopentyl glycol diglycidyl ether, 1,2,7,8-diepoxyoctane, 1,6-dimethylol perfluorohexa Diglycidyl ether, 4,4'-bis (2,3-epoxypropoxyperfluoroisopropyl) diphenyl ether, 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, 1,2,5,6- Diepoxy-4,7-methanoperhydroindene, 2- (3,4-epoxycyclohexyl) -3 ', 4'-epoxy-1,3-dioxane-5-spirocyclohexane, 1,2-ethylenedioxy-bis (3,4-epoxycyclohexylmethane), 4 ', 5'-epoxy-2'-methylcyclohexylmethyl-4,5-epoxy-2-methylcyclohexanecarboxylate, ethylene glycol-bis (3,4-epoxycyclohexane Carboxylate), bis- (3,4-epoxycyclohexylmethyl) adipate, di-2,3-epoxycyclopentyl ether, vinyl-2-chloroethyl ether, vinyl-n-butyl ether, Reethylene glycol divinyl ether, 1,4-cyclohexanemethanol divinyl ether, trimethylol methane trivinyl ether vinyl glycidyl ether, Ardite CY175 (Nippon Chiba Gaigi), Ardite CY177 (Nippon Chiba Gaigi), Ardite CY179 (Nippon Chiba Gaigi), Ardaito CY184 (Nippon Chiba Geigi) , Ardite CY192 (Nippon Chiba Gaigi). These can be used in combination of two or more.

  Examples of the polysilsesquioxane include polymethylsilsesquioxane, polyphenylsilsesquioxane, polyphenyl-methylsilsesquioxane and the like having a molecular weight of about 300 to 10,000, preferably about 1,000 to 8,000. Examples thereof include cage-type silsesquioxanes such as regular and ladder-type polysilsesquioxanes and polyhydridosilsesquioxanes (T8 cubes).

  The photopolymerization initiator is not particularly limited as long as it initiates polymerization of the above polymerizable monomer when irradiated with light of a predetermined intensity, and may be a cationic photoion polymerization initiator. However, a radical photopolymerization initiator is preferred. Examples of the photo radical polymerization initiator include azo compounds, azide compounds, organic peroxides, onium salts, bisimidazole derivatives, titanocene compounds, iodonium salts, organic thiol compounds, halogenated hydrocarbon derivatives, and the like. Of these, titanocene compounds are preferred.

  The titanocene compound is not particularly limited, and specifically, di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, di-cyclopentadienyl-Ti-bis. -2,3,4,5,6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopenta Dienyl-Ti-bis-2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-di-fluorophen-1-yl, di-cyclopentadienyl -Ti-bis-2,4-di-fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di- Methylcyclo Interdienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-methylcyclopenta And dienyl-Ti-bis-2,6-difluoro-3- (pyr-1-yl) -phen-1-yl.

The radical photopolymerization initiator of this embodiment may be used alone or in combination with a sensitizer that is a component that absorbs light. Specific examples of preferred sensitizers include, for example, 2,6-diethyl-1,3,5,7,8-pentamethylpyromethene-BF ₂ complex, 1,3,5,7,8-pentamethylpyrrole. Pyromethene complexes such as methene-BF ₂ complexes; xanthene dyes such as eosin, ethyl eosin, erythrosine, fluorescein, rose bengal; 1- (1-methylnaphtho [1,2-d] thiazole-2 (1H) -ylidene -4- (2,3,6,7) tetrahydro-1H, 5H-benzo [ij] quinolizin-9-yl) -3-buten-2-one, 1- (3-methylbenzothiazole-2 (3H) -Ketothiazoline compounds such as ylidene-4- (p-dimethylaminophenyl) -3-buten-2-one; 2- (p-dimethylaminostyryl) -naphtho [1,2-d] thio Azole, styryl or phenylbutadienyl heterocyclic compounds such as 2- [4- (p-dimethylaminophenyl) -1,3-butadienyl] -naphtho [1,2-d] thiazole; 2,4-diphenyl- 6- (p-dimethylaminostyryl) -1,3,5-triazine, 2,4-diphenyl-6-(([2,3,6,7] tetrahydro-1H, 5H-benzo [ij] quinolidine-9 A triazine compound such as -yl) -1-ethen-2-yl) -1,3,5-triazone; 9-phenanthryl-(([2,3,6,7] tetrahydro-1H, 5H-benzo [ij ] Aminophenyl unsaturated ketone compounds such as quinolizin-9-yl) -1-ethen-2-yl) ketone, 2,5-bis (p-dimethylaminocinnamylidene) cyclopentanone; 10, 15, 20-tetraphenylporphyrin, and the like porphyrin, such as hematoporphyrin poly Villingen. Of these, pyrromethene complex.

  Subsequently, the metal oxide particles according to the present embodiment will be described.

As shown in FIG. 2, the metal oxide particle 100 of the hologram recording material according to the present embodiment has a metal atom M and a hydrophobic group R bonded to the metal atom M on the surface of the metal oxide particle main body 99. -M-R ¹ _n groups having ^1, a is coupled. Here, n is a natural number, and when there are a plurality of R ¹ , the hydrophobic groups R ¹ may be the same or different from each other. The metal atom M is selected from the group consisting of titanium, aluminum, zirconium, and chromium. Here, the metal atoms M in the two —M—R ¹ _n groups bonded to the metal oxide particle main body 99 may be bonded to each other via oxygen. In addition, the —M—R ¹ _n group is usually bonded to an oxygen atom of the metal oxide particle main body 99.

As shown in FIG. 3, such a metal oxide particle 100 can dehydrate and condense a metal oxide particle having a hydroxyl group on the surface with a hydrophobic group R ¹ on the metal atom M and a hydroxyl group on the surface of the metal oxide particle. It is obtained by surface treatment with a surface treatment agent ZM-R ¹ _{n to} which a functional group Z is bonded. That is, the functional group Z of the surface treatment agent Z-M-R ¹ _n causes a dehydration condensation reaction with the hydroxyl group on the surface of the metal oxide, and oxygen on the surface of the metal oxide particle and the metal atom M are combined, Metal oxide particles in which the M-R ¹ _n group is bonded and the hydrophobic group R ¹ is exposed on the surface are obtained.

  Here, the metal oxide particles are not particularly limited. For example, titanium oxide, silicon oxide, zinc oxide, aluminum oxide, antimony oxide, chromium oxide, cerium oxide, yttrium oxide, zirconium oxide, tin oxide, copper oxide, oxide Examples thereof include metal oxides such as iron, magnesium oxide, manganese oxide, holmium oxide, bismuth oxide, cobalt oxide, erbium oxide, gadolinium oxide, indium oxide, nickel oxide, strontium oxide, and ytterbium oxide. Among these, in particular, titanium oxide is preferable because it has a high refractive index of 2.5, so that the difference in refractive index from a polymerizable monomer (polymer) that is an organic substance can be increased and the diffraction efficiency can be sufficiently increased. When titanium oxide is used as the metal oxide particles, it is particularly preferable from the viewpoint of diffraction efficiency that a monomer containing fluorine having a relatively low refractive index is used as the polymerizable monomer.

The hydrophobic group R ¹ in the —M—R ¹ _n group bonded to the surface of such a metal oxide particle is not particularly limited. For example, the alkyl group having 1 to 10 carbon atoms which may have a substituent A phenyl group, a methacryl group, and an acryl group which may have a group and a substituent.

In addition, as the hydrophobic group R ^1, there are other —OCOR groups such as the following formula (1) (where R is an alkyl group), alkoxy groups such as the following formula (2), the following formula (3a) ( -P (OH)-(OR) ₂ group (wherein R is an alkyl group) as shown in 3b), -O-PO (OH) -O-PO (OR) ₂ group as shown in the following formula (4) ( Where R is an alkyl group), —OR ² NHR ³ NH ₂ group as represented by the following formula (5) (wherein R ² and R ³ are alkylene groups), and —O—SOO as represented by the following formula (6): -Ph-R group (where R is an alkyl group), alkyl acetoacetate group as shown in the following formula (7), acrylic group as shown in the following formula (8), methacryloxyethyl acetate as shown in the following formula (9) A hydrophobic group such as a group can be exemplified.

金属原子Ｍに結合する疎水基Ｒ¹の数は任意であり、複数有する場合には互いに同一でも異なっていても良い。疎水基Ｒ¹と金属原子Ｍとの結合様式は、任意であり、共有結合、配位結合、イオン結合等のいずれでも良い。

The number of hydrophobic groups R ¹ bonded to the metal atom M is arbitrary, and when there are a plurality of them, they may be the same or different. The bonding mode between the hydrophobic group R ¹ and the metal atom M is arbitrary, and may be any of a covalent bond, a coordinate bond, an ionic bond, and the like.

Further, hydroxyl groups and dehydration of the surface of the metal oxide particles of the surface treatment agent ZM-R ¹ _n for forming such metal atoms M and hydrophobic groups R ¹ bonded thereto on the surfaces of the metal oxide fine particles. Examples of the condensable functional group Z- include an alkoxy group which is R ² —O—, a hydroxy group, and a group represented by the formula (10). The R ² group of the alkoxy group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably a methyl group, an ethyl group, or a propyl group. As the equation (10) R ^4, -CH ₂ -COO- group, -CH ₂ -CH ₂ - group, and the like.

また、表面処理剤Ｚ−Ｍ−Ｒ¹ _nの疎水基Ｒ¹は、上述の通りである。

Further, the hydrophobic group R ¹ of the surface treatment agent ZM-R ¹ _n is as described above.

  Here, the bonding mode between the functional group Z and the metal atom M is arbitrary, and may be any of a covalent bond, a coordinate bond, an ionic bond, and the like.

  And as a specific example of a surface treating agent, the surface treating agent represented by (11) Formula and (12) Formula is mentioned, for example.

ここで、Ｒ²−Ｏ−、−Ｏ−Ｒ⁴−Ｏ−が官能基Ｚを示し、Ｍが上述の金属原子を示し、Ｒ¹が上述の疎水基を示す。疎水基Ｒ¹は互いに同一でも異なっても良い。

Here, R ² —O— and —O—R ⁴ —O— represent the functional group Z, M represents the above metal atom, and R ¹ represents the above hydrophobic group. The hydrophobic groups R ¹ may be the same as or different from each other.

As a specific example of the surface treating agent of the formula (11), when the metal atom M is titanium, the functional group Z is an isopropoxy group, the hydrophobic group is of the formula (1), and the functional group Z is C ₈ H ₁₇ O— containing a group of formulas (2) and (3a) as a hydrophobic group, a functional group Z being an isopropoxy group and having a molecule of formula (3b) as a hydrophobic group, a functional group Z is an isopropoxy group and the hydrophobic group is the formula (4), the functional group Z is the isopropoxy group and the hydrophobic group is the formula (5), the functional group Z is the isopropoxy group and the hydrophobic group is (6) What is a type | formula is mentioned.

Further, as a specific example of the surface treatment agent of the formula (12), when the metal atom M is titanium, the R ⁴ group is a —CH ₂ —COO— group and the hydrophobic group is a formula (4) , R ⁴ group is —CH ₂ —CH ₂ — group and the hydrophobic group is represented by formula (4).

  Further, as the surface treating agent in which the metal atom M is aluminum, the alkyl acetoacetate aluminum diisopropyl compound of the formula (13) having two isopropoxy groups as the functional group Z and the group of the formula (7) as the hydrophobic group. A complex that is a rate

また、金属原子Ｍがクロムである表面処理剤としては、官能基Ｚとしてヒドロキシ基を有し、疎水基として（８）式の基を有する（１４）式のクロム（ＩＩＩ）ヒドロキシアクリレートである錯体が挙げられる。

Further, as the surface treating agent in which the metal atom M is chromium, the complex is a chromium (III) hydroxyacrylate of the formula (14) having a hydroxy group as the functional group Z and a group of the formula (8) as a hydrophobic group. Is mentioned.

また、金属原子Ｍがジルコニウムである表面処理剤としては、官能基Ｚとしてノルマルプロポキシ基を有し、疎水基として（９）式の基を有する（１５）式のジルコニウムメタクリルオキシエチルアセトアセテートトリｎ−プロポキシドである錯体が挙げられる。

In addition, as the surface treating agent in which the metal atom M is zirconium, zirconium methacryloxyethyl acetoacetate tri-n having the formula (15) having a normal propoxy group as the functional group Z and a group of the formula (9) as the hydrophobic group. -Complexes that are propoxides.

ここで、ホログラム用記録材料３０における、金属酸化物粒子、重合可能なモノマー、光重合開始剤の重量分率は特に限定されないが、これら３つを１００重量部としたときに金属酸化物粒子を１０〜８０重量部、モノマーを１０〜８０重量部、光重合開始剤を０．０５〜２０重量部とすることが好ましい。

Here, the weight fraction of the metal oxide particles, the polymerizable monomer, and the photopolymerization initiator in the hologram recording material 30 is not particularly limited, but when these three are 100 parts by weight, the metal oxide particles It is preferable that 10 to 80 parts by weight, 10 to 80 parts by weight of the monomer, and 0.05 to 20 parts by weight of the photopolymerization initiator.

  When such a hologram recording medium is irradiated with interference fringes formed by superimposing reference light and recording light, a monomer that can be polymerized by a photopolymerization initiator in a strong light portion (hereinafter referred to as a light irradiation region) Is photopolymerized to form a polymer. As a result, the monomer concentration in the light irradiation region is reduced, so that monomer is supplied to the light irradiation region by diffusion from the adjacent weak light portion (hereinafter referred to as the light non-irradiation region), and polymer formation is further performed in the light irradiation region. Is promoted. On the other hand, the metal oxide particles in the light-irradiated region are pushed out of the light-irradiated region to form a polymer there, and move to the adjacent non-light-irradiated region by diffusion. Therefore, the polymer concentration is high in the light irradiated region, whereas the metal oxide concentration is high in the light non-irradiated region, resulting in a difference in composition. Then, when the hologram recording medium as the hologram recording material in which the interference fringes are recorded in this way is irradiated with the reference light, it corresponds to the refractive index difference due to the difference in composition between the light irradiation region and the light non-irradiation region. Due to the diffraction effect, interference fringes are reproduced.

  According to the hologram recording material of the present embodiment, since the surface of the metal oxide particles is covered with the hydrophobic group, the metal oxide particles and the monomer can be mixed well. As a result, each other can be dispersed well, and the transparency of the hologram recording material is enhanced. Accordingly, since the light for forming the interference fringes and the reference light for reproduction reach the hologram recording material sufficiently, the diffraction efficiency is improved.

  Further, as in this embodiment, the hologram recording material having metal oxide particles treated with a surface treatment agent containing a metal atom selected from the group consisting of titanium, aluminum, zirconium, and chromium is a metal oxide. The diffraction efficiency is not only higher than when the surface of the particles is not hydrophobized, but also sufficiently higher than when the metal oxide particles are surface-treated with a surface treatment agent containing silicon.

  Compared to the case where metal oxide particles whose surface is hydrophobized with a surface treatment agent containing silicon (for example, a silane coupling agent) are used, the surface is hydrophobized by the surface treatment agent containing metal atoms of this embodiment. Although the reason why the diffraction efficiency is higher when treated is not clear, for example, metal oxide particles surface-treated with a silane coupling agent interact with a monomer or a polymer obtained by photopolymerization of this monomer. It is easy to prevent the diffusion of metal oxide particles from the light irradiation region to the light non-irradiation region during light irradiation and the monomer diffusion from the light non-irradiation region to the light irradiation region. It is conceivable that the difference in composition between the irradiated region and the non-light-irradiated region is difficult to occur.

  In contrast, the metal oxide particles surface-treated using the surface treatment agent having a metal atom according to the present embodiment are less likely to interact with the monomer or the polymer obtained by polymerizing the monomer, and the monomer or metal oxide. Since the particles are sufficiently diffused, it is considered that the difference in composition corresponding to the interference fringes is sufficiently expressed in the hologram recording material, and a hologram recording material having an excellent diffraction efficiency and high efficiency can be obtained.

  If titanium oxide having a refractive index of 2.5 is used as the metal oxide particle, the difference in refractive index from the monomer (polymer) that is an organic substance can be increased, so that the diffraction efficiency can be further increased. Can do. Here, when titanium oxide is used as the metal oxide particles, it is preferable to use a fluorine-containing monomer having a low refractive index among the organic monomers as the monomer.

  Needless to say, the hologram recording material may contain other components such as a plasticizer and a binder as long as the effects of the present embodiment can be maintained.

  In addition, the wavelength of the reference light or recording light used for hologram recording is preferably 250 to 500 nm. If the thickness is less than 250 nm, the absorption by the monomer increases, and light tends to hardly reach the depth of the hologram recording material. On the other hand, when it exceeds 500 nm, energy tends to be low, and it tends to be difficult to initiate polymerization even when a sensitizer is used.

  Next, a method for manufacturing such a hologram material and a hologram recording medium will be described.

  First, a metal alkoxide is prepared. The metal alkoxide is not particularly limited, and examples thereof include silicon alkoxide, aluminum alkoxide, titanium alkoxide, magnesium alkoxide, zirconium alkoxide, indium alkoxide, tin alkoxide, and the like, and these may be used in combination of two or more depending on the application. Is also possible. In particular, silicon alkoxide, titanium alkoxide, indium alkoxide, and tin alkoxide are preferable from the viewpoint of increasing the transparency of the hologram recording material and further increasing the difference in refractive index from the polymer (monomer).

  Examples of the silicon alkoxide include tetramethyl silicate, tetraethyl silicate, tetra n-propyl silicate, tetraisopropyl silicate, tetra n-butyl silicate and the like.

  Examples of the aluminum alkoxide include aluminum methylate, aluminum ethylate, aluminum isopropylate, mono sec-butoxyaluminum diisopropylate, and aluminum sec-butylate.

  Examples of the titanium alkoxide include tetraethoxytitanium, tetraisopropoxytitanium, and tetra n-butoxytitanium.

  Examples of the magnesium alkoxide include diethoxymagnesium.

  Examples of the zirconium alkoxide include zirconium t-butoxide, zirconium propoxide, zirconium ethoxide, zirconium 2-ethylhexoxide and the like.

  Examples of the indium alkoxide include indium hexafluoropentanedionate, indium methoxyethoxide, indium 2,4-pentanedionate, indium methyl (trimethyl) acetyl acetate, indium trifluoropentanedionate, and the like.

  Examples of the tin alkoxide include tetra-t-butoxytin, tin (II) ethoxide, tetra-i-propoxytin, tin (II) -2,4-pentandionate, and the like.

  Then, such a metal alkoxide is dissolved in a solvent to obtain a solution in which the metal alkoxide is dissolved. Here, the solvent is not particularly limited as long as it does not contain water, and examples thereof include alcohols such as IPA, ethanol, and methanol.

  Next, water is added to the solution in which the metal alkoxide is dissolved in the solvent. Here, in order to improve the controllability of the hydrolysis reaction of the metal alkoxide, it is preferable to add a solution containing water and a solvent other than water to the solution in which the metal alkoxide is dissolved. Here, the solvent is not particularly limited, but the same type as the solvent dissolving the metal alkoxide is preferable. Further, an acid or alkali may be added as a catalyst to a solution containing water and a solvent other than water. In this case, it is preferable to remove the catalyst in the product by solvent substitution described later.

  As an addition method, for example, it is preferable to supply a solution containing water by dropping or the like while stirring the solution in which the metal alkoxide is dissolved.

  As a result, the metal alkoxide is hydrolyzed to form a metal oxide-containing solution containing metal oxide fine particles (metal oxide sol) and a solvent containing added water. According to such hydrolysis of metal alkoxide, that is, the sol-gel method, the particle diameter of the metal oxide can be easily controlled by temperature, time, etc., and metal oxide fine particles having a desired particle diameter and little aggregation are obtained. A solution containing it is easily obtained.

  The particle size of the metal oxide particles thus obtained is not particularly limited, but is preferably 1 to 100 nm in order to increase dispersibility and increase diffusibility in the hologram recording material during light irradiation. 10 to 100 nm is more preferable.

  Here, it is preferable to remove water contained in the solvent of the metal oxide-containing solution. It is preferable that water or the like introduced in the hydrolysis step is removed from the metal oxide-containing solution because the solution drying time in the subsequent step can be easily controlled and solvent separation during drying can be suppressed. As a method for separating water, for example, a metal oxide-containing solution is centrifuged to separate it into a sol concentrated layer and a solvent layer, then the solvent layer is removed, and the sol concentrated layer is replaced with another organic solvent. That's fine.

  Thereby, unreacted or low-polymerization metal alkoxide can be removed from the metal oxide-containing solution. For this reason, the uniformity of polymerization during light irradiation can be made high, and the polymer and metal oxide fine particles can be diffused well in the hologram recording material. The difference in composition between the portions becomes large, the refractive index difference can be increased, and the diffraction efficiency can be increased. Although it does not specifically limit as another organic solvent, It is preferable to use the organic solvent in which the monomer added at a post process is easy to melt | dissolve. Specific examples of the solvent to be substituted include, for example, tetrahydrofuran, toluene, dichloromethane, chloroform and the like, although depending on the monomer added in the subsequent step.

  In addition, according to the above centrifugation operation, since removal of water and replacement | exchange of a solvent can be performed at once, it is suitable. Here, it is preferable to repeat the operation of diluting the substituted metal oxide-containing solution again with the solvent to be replaced and centrifuging to remove the solvent layer one or more times.

Next, a surface treatment agent is added to the metal oxide-containing solution to modify the surface of the metal oxide. As the surface treatment agent, the above-described surface treatment agent ZM-R ¹ _n is used.

Subsequently, a polymerizable monomer and a photopolymerization initiator that starts polymerization of the polymerizable monomer when irradiated with light are added to the metal oxide-containing solution surface-modified with the -M-R ¹ _n group. To do. Specifically, a solution containing a polymer, a photopolymerization initiator, and a solvent may be added. As the polymerizable monomer and the photopolymerization initiator, those described above can be used. Moreover, as a solvent, the same kind as the solvent of a metal oxide containing solution is preferable. Furthermore, it goes without saying that other additives such as a plasticizer and a binder may be added as necessary.

  Then, a solution containing metal oxide particles, a polymerizable monomer, and a photopolymerization initiator is applied to the surface of the substrate 20 as shown in FIG. 1, and the solvent is dried to record the hologram recording material 30 as a recording layer. Form. A known coating method such as a dropping method or a spin coating method can be used for coating the solution, and a known drying method such as heating or decompression can be used for drying the solvent.

  Furthermore, the hologram recording material 30 is completed by covering the hologram recording material 30 with a protective transparent plate 40 as necessary.

And according to this embodiment, since the surface of the metal oxide particles is treated with the surface treatment agent-M-R ¹ _n having a metal atom selected from the group consisting of titanium, aluminum, zirconium, and chromium, The diffraction efficiency of the hologram recording material is increased.

  The embodiment will be specifically described by way of examples.

(Example 1)
Here, titanium oxide particles formed by a sol-gel method were used. Titanium oxide sol TKS-251 20 wt% toluene solution manufactured by Teika as metal oxide particles, and Ajinomoto Fine-Techno Preact KR TTS (one isopropoxy group and —O—CO—C ₁₇ H ₃₅ as coupling agent) 1 part by weight of titanate having three groups), 50 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate as a polymerizable monomer, and 5 parts by weight of titanocene derivative (IRG-784, Ciba-Geigy) as a photo radical polymerization initiator Each part was mixed and dissolved.

  Next, a polyethylene terephthalate film having a thickness of 50 μm is pasted on both ends of the slide glass as a spacer, and a surface-modified titanium oxide sol, a polymerizable monomer and a photopolymerization initiator are placed in the center of the slide glass (region sandwiched between the spacers). The solution containing the solution was dropped and dried under reduced pressure for 24 hours to form a hologram recording material as a recording layer. Then, a hologram recording medium was produced by covering the hologram recording material with a slide glass.

  Here, the hologram recording material of this example showed sufficient transparency.

  Subsequently, with the apparatus shown in FIG. 4, two-beam interference exposure was performed to perform hologram recording, and the diffraction efficiency was measured.

Specifically, two-beam exposure was performed on the hologram recording medium 1 using a Doubled-YAG laser (wavelength λ = 532 nm) at an exposure power density of 5 mW / cm ² . That is, the light emitted from the YAG laser is divided into two by the half mirror 4 through the beam expander 3, and irradiated onto the hologram recording medium 1 through the mirrors 5 and 6, respectively, and interference fringes are recorded on the hologram recording material. Thus, a hologram recording medium 1 as a hologram recording product was obtained. Here, the neutral density filter 8 and the shutter 7 are not functioned.

  Subsequently, the optical path between the half mirror 4 and the mirror 5 is blocked by the shutter 7, and only the reference light attenuated by the neutral density filter 8 is applied to the hologram recording medium 1 as the hologram recording material. The hologram was reproduced, the reproduced light was detected by the detector 10, and the diffraction efficiency was measured. The diffraction efficiency was defined as the ratio of the intensity of the reproduced light reproduced to the intensity of the reference light irradiated for reproduction. The diffraction efficiency was sufficiently high at 41%.

(Example 2)
A hologram recording medium was produced in the same manner as in Example 1 except that 50 parts by weight of tin oxide (particle size 50 nm) was used as the metal oxide particles, and 200 parts by weight of toluene was used as the solvent. The hologram recording material was transparent. Further, as a result of recording / reproducing in the same manner, the diffraction efficiency was 37%.

(Comparative Example 1)
A hologram recording medium was produced in the same manner as in Example 1 except that 5 parts by weight of 3-aminopropyltrimethoxysilane (manufactured by Chisso Corporation) was used as the surface treating agent containing silicon atoms. The hologram recording material was transparent. As a result of recording / reproducing in the same manner, the diffraction efficiency was 32%.

(Comparative Example 2)
A hologram recording medium was produced in the same manner as in Example 1 except that no surface treating agent was used. The hologram recording material was white. Moreover, as a result of recording / reproducing in the same manner, the diffraction efficiency was 29%.

  The result of the diffraction efficiency is shown in FIG. As is apparent from the figure, according to the present invention, when a metal oxide particle that is not subjected to surface treatment is used, and a hologram recording material that uses metal oxide particles that are surface-treated using a surface treatment agent containing silicon. In comparison, it was revealed that a hologram recording material and a recording medium having high diffraction efficiency can be obtained.

It is sectional drawing of the recording medium for holograms concerning this embodiment. It is a schematic diagram which shows the surface of the metal oxide particle of the recording material for holograms concerning this embodiment. 4 is a reaction formula showing the state of surface treatment of the surface of metal oxide particles in the production of a hologram recording medium according to the present embodiment. It is a figure which shows the apparatus which records a hologram on the recording medium for hologram, and the apparatus which reproduces a hologram. It is a figure which shows the diffraction efficiency of Examples 1 and 2 and Comparative Examples 1 and 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Hologram recording medium, 30 ... Hologram recording material, 20 ... Base material, 100 ... Metal oxide particle.

Claims (7)

Metal oxide particles, a polymerizable monomer, and a photopolymerization initiator that initiates polymerization of the monomer when irradiated with light,
The metal oxide particles are surface-treated with a surface treatment agent in which a hydrophobic group and a functional group capable of dehydration condensation with a hydroxyl group on the surface of the metal oxide particles are bonded to a metal atom,
The hologram recording material, wherein the metal atom is selected from the group consisting of titanium, aluminum, zirconium, and chromium. Metal oxide particles, a polymerizable monomer, and a photopolymerization initiator that initiates polymerization of the monomer when irradiated with light,
On the surface of the metal oxide particles, -M-R ¹ _n group (where M is any element selected from the group consisting of titanium, aluminum, zirconium and chromium, R ¹ is a hydrophobic group, n is Hologram recording material combined with a natural number). A base material, and a recording layer formed on the base material,
The recording layer includes metal oxide particles, a polymerizable monomer, and a photopolymerization initiator that initiates polymerization of the monomer when irradiated with light,
The metal oxide particles are surface-treated with a surface treatment agent in which a hydrophobic group and a functional group capable of dehydration condensation with a hydroxyl group on the surface of the metal oxide particles are bonded to a metal atom,
The hologram recording medium wherein the metal atom is selected from the group consisting of titanium, aluminum, zirconium, and chromium. A base material, and a recording layer formed on the base material,
The recording layer includes metal oxide particles, a polymerizable monomer, and a photopolymerization initiator that initiates polymerization of the monomer when irradiated with light,
On the surface of the metal oxide particles, -M-R ¹ _n group (where M is any element selected from the group consisting of titanium, aluminum, zirconium and chromium, R ¹ is a hydrophobic group, n is Hologram recording medium combined with natural number). A base material, and a recording layer formed on the base material and recorded with interference fringes,
The recording layer includes metal oxide particles and a polymer formed by photopolymerization,
The metal oxide particles are surface-treated with a surface treatment agent in which a hydrophobic group and a functional group capable of dehydration condensation with a hydroxyl group on the surface of the metal oxide particles are bonded to a metal atom,
The hologram recording medium wherein the metal atom is selected from the group consisting of titanium, aluminum, zirconium, and chromium. A base material, and a recording layer formed on the base material and recorded with interference fringes,
The recording layer includes metal oxide particles and a polymer formed by photopolymerization,
On the surface of the metal oxide particles, -M-R ¹ _n group (where M is any element selected from the group consisting of titanium, aluminum, zirconium and chromium, R ¹ is a hydrophobic group, n is Hologram recording medium combined with natural number). The surface of the metal oxide particle is treated with a surface treatment agent in which a hydrophobic group and a functional group capable of dehydration condensation with a hydroxyl group on the surface of the metal oxide particle are bonded to a metal atom selected from the group consisting of titanium, aluminum, zirconium, and chromium. And a step of mixing a surface-treated metal oxide particle, a polymerizable monomer, and a photopolymerization initiator that polymerizes the monomer when irradiated with light. Method.

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